Population Dynamics and the Microbiome in a Wild Boreal Mammal: The Snowshoe Hare Cycle and Impacts of Diet, Season and Predation Risk.

The North American boreal forest is a massive ecosystem, and its keystone herbivore is the snowshoe hare (Lepus americanus). Hares are exposed to considerable environmental extremes in diet and weather, food availability, and predation risk. Gut microbiomes have been suggested to facilitate adaptive animal responses to environmental change, but severe environmental challenges to homeostasis can also disrupt host-microbiome relationships.

Sex-specific maternal programming of corticosteroid-binding globulin by predator odour.

Predation is a key organizing force in ecosystems. The threat of predation may act to programme the endocrine hypothalamic-pituitary-adrenal axis during development to prepare offspring for the environment they are likely to encounter. Such effects are typically investigated through the measurement of corticosteroids (Cort).

The impact of variable predation risk on stress in snowshoe hares over the cycle in North America's boreal forest: adjusting to change.

The boreal forest is one of the world's ecosystems most affected by global climate warming. The snowshoe hare, its predators, and their population dynamics dominate the mammalian component of the North American boreal forest. Our past research has shown the 9-11-year hare cycle to be predator driven, both directly as virtually all hares that die are killed by their predators, and indirectly through sublethal risk effects on hare stress physiology, behavior, and reproduction.

Maternal effects in mammals: Broadening our understanding of offspring programming.

The perinatal period is a sensitive time in mammalian development that can have long-lasting consequences on offspring phenotype via maternal effects. Maternal effects have been most intensively studied with respect to two major conditions: maternal diet and maternal stress. In this review, we shift the focus by discussing five major additional maternal cues and their influence on offspring phenotype: maternal androgen levels, photoperiod (melatonin), microbiome, immune regulation, and milk composition.

Hair cortisol as a reliable indicator of stress physiology in the snowshoe hare: Influence of body region, sex, season, and predator-prey population dynamics.

Hair cortisol concentration is increasingly used as a convenient, non-invasive, and integrative measure of physiology and health in natural populations of mammals. However, the use of this index is potentially confounded by individual variation in body region-specific differences in cortisol deposition rates. Here we examine correlations in cortisol concentrations in hair collected from the ear, shoulder, and thigh of wild snowshoe hares, Lepus americanus, as well as the influence of sex on cortisol measurements.

Integrating Ecological and Evolutionary Context in the Study of Maternal Stress.

Maternal stress can prenatally influence offspring phenotypes and there are an increasing number of ecological studies that are bringing to bear biomedical findings to natural systems. This is resulting in a shift from the perspective that maternal stress is unanimously costly, to one in which maternal stress may be beneficial to offspring. However, this adaptive perspective is in its infancy with much progress to still be made in understanding the role of maternal stress in natural systems.

Impact of high predation risk on genome-wide hippocampal gene expression in snowshoe hares.

The population dynamics of snowshoe hares (Lepus americanus) are fundamental to the ecosystem dynamics of Canada's boreal forest. During the 8- to 11-year population cycle, hare densities can fluctuate up to 40-fold. Predators in this system (lynx, coyotes, great-horned owls) affect population numbers not only through direct mortality but also through sublethal effects.